Write the chemical reactions involved in the extraction of gold by the cyanide process. Also, give the role of zinc in the extraction.

Reactions Involved:

4Au(s) + 8CN^–(aq) + 2H₂O(aq) + O₂(g)  →  4[Au(CN)₂]^–(aq) + 4OH^–(aq)

2[Au(CN)₂]^–(aq) + Zn(s) → 2Au(s) + [Zn(CN)₄]^2- (aq)

Role of Zinc in this reaction – Reducing Agent